351
the conversion gradually. GVL can further be catalytically converted into valuable
chemicals and fuels such as 1,4-pentanediol, 2-methyltetrahydrofuran, valeric biofuels, 5-nonanone, and α-methylene-γ-valerolactone (Scheme 3).
3.2 Synthesis of 1,4-Pentanediol
and 2-Methyltetrahydrofuran from LA
The use of GVL as a liquid fuel is restricted due to its high solubility in water.
Hence, researchers are now focusing on converting GVL to another useful product,
which can be further utilized as a biofuel additive. The hydrogenation of GVL produces other useful fuel additives like 1,4-pentanediol (1,4-PDO) and
2- methyltetrahydrofuran (2-MTHF). Palkovits et al. [34] have reported the catalytic
hydrogenation reaction of GVL to produce 2-MTHF in a solvent-free reaction condition using Ru/C as heterogeneous catalyst. The conversion of GVL is found to be
about 99% with 43% yield of 2-MTHF at 190 °C and 24-h reaction time. Du et al.
have reported the conversion of GVL to 2-MTHF with 98% conversion and 93%
selectivity over an inexpensive Cu catalyst. They have also reported that if the reaction is carried out at low temperature in the presence of calcined Cu catalyst and H 2
instead of air, the formation of 1,4-pentanediol is observed [35] (Scheme 4).
Direct conversion of LA into 2-MTHF in the presence of noble metal catalysts
using 1,4-dioxane and water as a solvent system is reported by Elliott and Frye [35].
The conversion proceeds via the formation of GVL and 1,4-PDO as the reaction
intermediates. The literature is also available for the conversion of LA into 2-MTHF
via GVL using both homogeneous and heterogeneous catalyst systems. Leiner et al.
have reported the homogeneous catalyst system based on Ru with acidic additives
to produce 2-MTHF from LA. The best performance, i.e., 92% yield of 2-MTHF,
was observed for the Ru(acac) 3 /triphos catalyst with cooperation of NH 4 PF 6 and
acidic ion liquid additives at 10 MPa H 2 and 160 °C reaction temperature [36].
O
O
OH
O
O
OH
+
H 2
OH
O
catalyst
Levulinic Acid
4-Hydropentanoic Acid
(4-HPA)
GVL
-H 2 O
Scheme 3 Synthesis of GVL from levulinic acid
Solid Acid-Catalyzed Esterification of Levulinic Acid for Production of Value-Added…
the conversion gradually. GVL can further be catalytically converted into valuable
chemicals and fuels such as 1,4-pentanediol, 2-methyltetrahydrofuran, valeric biofuels, 5-nonanone, and α-methylene-γ-valerolactone (Scheme 3).
3.2 Synthesis of 1,4-Pentanediol
and 2-Methyltetrahydrofuran from LA
The use of GVL as a liquid fuel is restricted due to its high solubility in water.
Hence, researchers are now focusing on converting GVL to another useful product,
which can be further utilized as a biofuel additive. The hydrogenation of GVL produces other useful fuel additives like 1,4-pentanediol (1,4-PDO) and
2- methyltetrahydrofuran (2-MTHF). Palkovits et al. [34] have reported the catalytic
hydrogenation reaction of GVL to produce 2-MTHF in a solvent-free reaction condition using Ru/C as heterogeneous catalyst. The conversion of GVL is found to be
about 99% with 43% yield of 2-MTHF at 190 °C and 24-h reaction time. Du et al.
have reported the conversion of GVL to 2-MTHF with 98% conversion and 93%
selectivity over an inexpensive Cu catalyst. They have also reported that if the reaction is carried out at low temperature in the presence of calcined Cu catalyst and H 2
instead of air, the formation of 1,4-pentanediol is observed [35] (Scheme 4).
Direct conversion of LA into 2-MTHF in the presence of noble metal catalysts
using 1,4-dioxane and water as a solvent system is reported by Elliott and Frye [35].
The conversion proceeds via the formation of GVL and 1,4-PDO as the reaction
intermediates. The literature is also available for the conversion of LA into 2-MTHF
via GVL using both homogeneous and heterogeneous catalyst systems. Leiner et al.
have reported the homogeneous catalyst system based on Ru with acidic additives
to produce 2-MTHF from LA. The best performance, i.e., 92% yield of 2-MTHF,
was observed for the Ru(acac) 3 /triphos catalyst with cooperation of NH 4 PF 6 and
acidic ion liquid additives at 10 MPa H 2 and 160 °C reaction temperature [36].
O
O
OH
O
O
OH
+
H 2
OH
O
catalyst
Levulinic Acid
4-Hydropentanoic Acid
(4-HPA)
GVL
-H 2 O
Scheme 3 Synthesis of GVL from levulinic acid
Solid Acid-Catalyzed Esterification of Levulinic Acid for Production of Value-Added…